1. Field of the Invention
The present invention relates to a plasma display panel (PDP), and more particularly, a PDP having an improved structure that may provide a high level of discharge stability.
2. Discussion of the Background
Generally, in a PDP, applying a predetermined voltage to electrodes having a gas filled between them generates a glow discharge, which generates ultraviolet rays that excite a phosphor layer to emit light, thereby displaying an image.
PDPs can be classified as direct current (DC) PDPs, alternating current (AC) PDPs, or hybrid PDPs according to their driving methods. A PDP can also be classified as a two-electrode type or a three-electrode type according to the number of electrodes. A DC PDP includes an auxiliary electrode to induce an auxiliary discharge, and an AC PDP includes an address electrode for improving addressing speed by separating an address discharge and a sustain discharge. Also, the AC PDP can be classified as an opposing discharge type and a surface discharge type according to discharge electrode arrangement. The opposing discharge type may include two sustain electrodes disposed on two substrates, respectively, to generate a discharge perpendicularly to the panel, and the surface discharge type may include two sustain electrodes disposed on one substrate to generate the discharge on a surface of the substrate.
FIG. 1 is a perspective view of a conventional surface discharge AC PDP.
The PDP 10 includes an upper substrate 11 and a lower substrate 21 facing the upper substrate 11 and substantially parallel to the upper substrate 11.
A sustain electrode pair 12 includes a common electrode 13 and a scan electrode 14, which are formed on a lower surface of the upper substrate 11. A discharge gap separates the common electrode 13 from the scan electrode 14.
The common electrode 13 and the scan electrode 14 include transparent electrodes 13a and 14a and bus electrodes 13b and 14b, respectively. The bus electrodes 13b and 14b may be formed along edges of the transparent electrodes 13a and 14a to apply voltages to the transparent electrodes 13a and 14a. An upper dielectric layer 15 covers the sustain electrode pairs 12, and a protective layer 16 covers the upper dielectric layer 15.
Additionally, address electrodes 22 may be formed on a surface of the lower substrate 21 facing the uppers substrate 11 and substantially perpendicular to the sustain electrode pairs 12. Areas where the address electrodes 22 and the sustain electrode pairs 12 cross each other become unit discharge cells (i.e. sub-pixels).
A lower dielectric layer 23 covers the address electrodes 22. Stripe-shaped barrier ribs 24 may be formed on the lower dielectric layer 23 to define discharge regions 25. A phosphor layer 26 is formed in the discharge regions 25, and a discharge gas is filled in the discharge regions 25. The phosphor layer 26 may include red, green, and blue phosphor layers 26R, 26G, and 26B according to the color of light the phosphor materials emit.
A PDP having the above structure may operate as follows.
Applying an address discharge voltage between an address electrode 22 and a scan electrode 14 generates an address discharge, which forms wall charges in the addressed discharge cell. Next, applying a sustain discharge voltage between the common electrode 13 and the scan electrode 14 of the addressed discharge cell generates a sustain discharge. Charges generated by the sustain discharge collide into the discharge gas, thereby forming plasma, which generates ultraviolet rays. The ultraviolet rays excite the phosphor layer 26, thereby displaying an image on the panel.
As FIG. 2 shows, the red, green, and blue phosphor layers 26R, 26G, and 26B may have the same height h as the barrier ribs h2. Here, the height h1 of the phosphor layer 26 is a straight distance between a lower surface of the barrier rib 24 and a highest point to which the phosphor layer 26 extends, and the height h2 of the barrier rib 24 is a straight distance between the lower surface of the barrier rib 24 and an upper surface of the barrier rib 24.
Typically used red and blue phosphor materials have positive polarities, while the green phosphor material typically has a negative polarity. If the red, green, and blue phosphor is layers have the same height as the barrier ribs, the address voltage for the green phosphor layer may be higher than for the red and blue phosphor layers. In order to solve this problem, Japanese Laid-open Patent No. 2001-236893 discloses a PDP in which negative polarity green phosphor material is mixed with positive polarity green phosphor material to change the phosphor material's polarity. However, changing the green phosphor material's polarity may change the address discharge characteristics, which may affect the following sustain discharge. Therefore, it is desirable to design a green phosphor layer that is capable of obtaining a stable sustain discharge.